Genetics - Real-life applications

The Genetics Revolution

In the modern world genetics plays a part in more dramatic
breakthroughs than any other

A
SCIENTIST STUDIES THE ARRANGEMENT OF CHROMOSOME PAIRS
,
THE THREADLIKE
DNA-
CONTAINING BODIES IN CELLS THAT CARRY GENETIC INFORMATION
. T
HE
H
UMAN
G
ENOME
P
ROJECT IS WORKING TO COMPLETE A MAP OUT
-
LINING THE LOCATION AND FUNCTION OF THE GENES IN HUMAN CELLS
. (

field of biological study. These breakthroughs have an impact in a
wide variety of areas, from curing diseases to growing better
vegetables to catching criminals. The field of genetics is in the
midst of a revolution, and at the center of this exciting (and, to
some minds, terrifying) phenomenon is the realm of genetic
engineering: the alteration of genetic material by direct intervention
in genetic processes. In agriculture, for instance, genes are
transplanted from one organism to another to produce what are known as
transgenic
animals or plants. This approach has been used to reduce the amount
of fat in cattle raised for meat or to increase proteins in the milk
produced by dairy cattle. Fruits and vegetables also have been
genetically engineered so that they do not bruise easily or have a
longer shelf life.

Not all of the work in genetics is genetic engineering per se; in the
realm of law, for instance, the most important application of genetics
is genetic fingerprinting. A genetic fingerprint is a sample of a
person's DNA that is detailed enough to distinguish it from the
DNA of all others. The genetic fingerprint can be used to identify
whether a man is the father of a particular child (i.e., to determine
paternity), and it can be applied in the solving of crimes. If
biological samples can be obtained from a crime scene—for
example, skin under the fingernails of a murder victim, presumably the
result of fighting against the assailant in the last few moments of
life—it is possible to determine with a high degree of accuracy
whether that sample came from a particular suspect. The use of DNA in
forensic science is discussed near the conclusion of this essay.

THE REVOLUTION IN MEDICINE.

Some of the biggest strides in genetic engineering and related fields
are taking place, not surprisingly, in the realm of medicine. Genetic
engineering in the area of health is aimed at understanding the causes
of disease and developing treatments for them: for example,
recombinant DNA (a DNA sequence from one species that is combined with
the DNA of another species) is being used to develop antibiotics,
hormones, and other disease-preventing agents. Vaccines also have been
genetically re-engineered to trigger an immune response that will
protect against specific diseases. One approach is to remove genetic
material from a diseased organism, thus making the material weaker and
initiating an immune response without causing the disease. (See
Immunity and Immunology for more about how vaccines work.)

Gene therapy is another outgrowth of genetics. The idea behind gene
therapy is to introduce specific genes into the body either to correct
a genetic defect or to enhance the body's capabilities to fight
off disease and repair itself. Since many inherited or genetic
diseases are caused by the lack of an enzyme or protein, scientists
hope one day to treat the unborn child by inserting genes to provide
the missing enzyme. (For more about inherited disorders, see the
essays Disease, Noninfectious Diseases, and Mutation.)

THE HUMAN GENOME PROJECT.

One of the most exciting developments in genetics is the initiation of
the Human Genome Project, designed to provide a complete genetic map
outlining the location and function of the 40,000 or so genes that are
found in human cells. (A genome is all of the genetic material in the
chromosomes of a particular organism.) With the completion of this
map, genetic researchers will have easy access to specific genes, to
study how the human body works and to develop therapies for diseases.
Gene maps for other species of animals also are being developed.

The project had its origins in the 1990s, with the efforts of the
United States Department of Energy (DOE) and the National Institutes
of Health (NIH). The NIH connection is probably clear enough, but the
DOE's involvement at first might seem strange. What, exactly,
does genetics have to do with electricity, petroleum, and other
concerns of the DOE? The answer is that the DOE grew out of agencies,
among them the Atomic Energy Commission (AEC), established soon after
the explosion of the two atomic bombs over Japan in 1945. Even at that
early date, educated nonscientists understood that the radioactive
fallout produced from nuclear weaponry can act as a mutagen;
therefore, Congress instructed the AEC to undertake a broad study of
genetics and mutation and the possible consequences of exposure to
radiation and the chemical by-products of energy production.

Eventually, scientists in the AEC and, later, the DOE recognized that
the best way to undertake such a study was to analyze the entire scope
of the human genome. The project formally commenced on October 1,
1990, and is scheduled for completion in the middle of the first
decade of the twenty-first century. Upon completion, the Human Genome
Project will provide a vast store of knowledge and no doubt will lead
to the curing of many diseases.

Still, there are many who question the Human Genome Project in
particular, and genetic engineering in general, on ethical grounds,
fearing that it could give scientists or governments

too much power, unleash a Nazi-style eugenics (selective breeding)
program, or result in horrible errors, such as the creation of deadly
new diseases. In fact, it is impossible to search "genetic
engineering" on the World Wide Web without coming across the
Web sites of literally dozens and dozens of agencies, activist groups,
and individuals opposed to genetic engineering and the mapping of the
human genome. For more about the Human Genome Project, genetic
engineering, and their opponents, see Genetic Engineering.

Genetics in Forensic Science

Forensic science, as we noted earlier, is the application of science
to matters of law. It is based on the idea that a criminal always
leaves behind some kind of material evidence that, through careful
analysis, can be used to determine the identity of the
perpetrator—and to exonerate someone falsely accused. Among
those forms of material evidence of interest to forensic scientists
working in the field of genetics are blood, semen, hair, saliva, and
skin, all of which contain DNA that can be analyzed. In addition,
there are areas of forensic science that rely on biological study,
though not in the area of genetics: blood typing as well as the
analysis of fingerprints or bite marks, both of which have patterns
that are as unique to a single individual as DNA is.

One of the first detectives to use science, including biology and
medicine, in solving crimes was a fictional character: Sherlock
Holmes, whose creator, the British writer Sir Arthur Conan Doyle
(1859-1930), happened to be a physician as well. The first
full-fledged (and real) police practitioner of forensic science was
the French police official Alphonse Bertillon (1853-1914), who
developed an identification system that consisted of a photograph and
11 body measurements, including dimensions of the head, arms, legs,
feet, hands, and so on, for each individual. Bertillon claimed that
the likelihood of two people having the same measurements for all 11
traits was less than one in 250 million. In 1894 fingerprints, which
were easier to use and more unique than body measurements, were added
to the Bertillon system.

Fingerprints, unlike DNA, are unique to the individual; indeed,
identical twins have the same DNA but different fingerprints. Mark
Twain (1835-1910) could not have known this in 1894, when he published
The Tragedy of Pudd'nhead Wilson, and the Comedy of Those
Extraordinary Twins.
Nonetheless, the story involves a murder committed by one man and
blamed on his twin, who eventually is exonerated on the basis of
fingerprint evidence—still a new concept at the time. In some
situations, however, fingerprint evidence may be unavailable, and
though law-enforcement agencies have developed extraordinary
techniques for analyzing nearly invisible (i.e., latent) prints,
sometimes this is still not enough.

THE SIMPSON CASE AND THE CONTROVERSY OVER DNA EVIDENCE.

For example, in the infamous murder of Nicole Brown Simpson and Ron
Goldman on June 12, 1994, fingerprint evidence would have been
ineffective in the case against the suspect, the former football star
and actor O. J. Simpson. Since Nicole Simpson was his ex-wife,

O. J. S
IMPSON REACTS TO THE JURY
'
S VERDICT
. D
ESPITE
DNA
EVIDENCE THAT LINKED BLOOD AT THE CRIME SCENE WITH BLOOD IN HIS
CAR
,
THE JURY FOUND HIM NOT GUILTY OF DOUBLE MURDER
. (

AP/WIde World Photos

.
Reproduced by permission.
)

the appearance of his prints at the scene of her murder in her Los
Angeles home could be explained away easily, even though she had taken
out a restraining order against her former husband (who she had
accused of spousal abuse) some time before the murder. Rather than
fingerprints, the prosecution in his murder trial used DNA evidence
connecting blood at the crime scene with blood found in
Simpson's vehicle. (Some of this blood was apparently his own,
since he had mysterious cuts on his hands that he could not explain to
police officers.)

A jury found Simpson not guilty on October 3, 1995, and jurors later
claimed that the prosecution had failed to make a strong case using
DNA evidence. Furthermore, they cited police contamination of the DNA
evidence, which had been established in their minds by
Simpson's defense team, as a cause for reasonable doubt
concerning Simpson's guilt. In fact, assuming that the defense
was fully justified in this claim, that would have meant only that the
DNA samples would have been
less
(not more) likely to convict Simpson.

At the same time, a number of legitimate concerns regarding the use of
DNA evidence were raised by experts for the defense in the Simpson
trial. Samples can become contaminated and thus difficult to read;
small samples are difficult for analysts to work with effectively; and
results are often open to interpretation. Furthermore, the outcome of
the Simpson case illustrates the fact that findings based on DNA
evidence are not readily understood by non-specialists, and may not
make the best basis for a case-particularly in one so fraught with
controversy. The prosecution based its case almost entirely on
extremely technical material, explained in excruciating detail by
experts who had devoted their lives to studying areas that are far
beyond the understanding of the average person. Attempting to wow the
jurors with science, the prosecution instead seemed to create the
impression that DNA evidence was some sort of hocus-pocus invented to
frame an innocent man. Simpson went free, though the jury in a 1996
civil trial (which took a much simpler approach, eschewing complicated
DNA testimony) found him guilty.

DNA EVIDENCE SUCCESS STORIES.

Because of the Simpson case, the use of DNA evidence gained something
of a bad name. Nonetheless, it has been successful in less high
profile cases, beginning in 1986, when English police tracked down a
rapist and murderer by collecting blood samples from some 2,000 men.
One of them, named Colin Pitchfork, paid another man to provide a
sample in his place. This attracted the attention of the police, who
tested his DNA and found their man.

Since that time, DNA evidence has been used in more than 24,000 cases
and has aided in the conviction of about 700 suspects. The DNA in such
cases is not always obtained from a human subject. In the
investigation of the May 1992 murder of Denise Johnson in Arizona, a
homicide detective found two seed pods from a paloverde tree in the
bed of a pickup truck owned by the suspect, Mark Bogan. The accused
man admitted having known the victim but denied ever having been near
the site where her body was found. It so happened that there was a
paloverde tree at the site, and testing showed that the DNA in the
pods on his truck bed matched that of the tree itself. Bogan became
the first suspect ever convicted by a plant.

On the other hand, in some cases, DNA evidence has cleared a suspect
falsely accused. Such was the case with Kerry Kotler, convicted in
1981 for rape, robbery, and burglary and sentenced to 25-50 years in
jail. In 1988, Kotler began petitioning for DNA analysis, which
subsequently showed that his DNA did not match that of the rapist, who
had left a semen sample in the victim's underwear. Kotler was
released in December 1992 and in March 1996 was awarded $1.5 million
in damages for his wrongful imprisonment. The story does not end
there, however. Kotler's case turned out to be one of the more
bizarre in the annals of forensic DNA testing. Perhaps he did not
commit the first rape, but a month after he received the damage award,
he was on his way back to prison for the August 1995 rape of another
victim. This time prosecutors showed that Kotler's semen
matched samples taken from his victim's clothing—and to
prove their case, they used DNA testing.

User Contributions:

Dear Sir, The article is very informative. It added a lot to my knowledge. I am a student of Applied Genetics at PG level. Will you please clarify whether 'Applied Genetics' is part of 'Life Sciences'? I am putting this question because one Asst Professor in a science college expressed his doubts about my eligibility for being appointed as a lecturer in a biology department. I will be very grateful for your reply.

With warm Regards,

Deepa V.

Comment about this article, ask questions, or add new information about this topic: